81637744 has 10 divisors (see below), whose sum is σ = 158173160. Its totient is φ = 40818864.

The previous prime is 81637739. The next prime is 81637753. The reversal of 81637744 is 44773618.

It is a junction number, because it is equal to n+sod(n) for n = 81637697 and 81637706.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2551164 + ... + 2551195.

It is an arithmetic number, because the mean of its divisors is an integer number (15817316).

Almost surely, 2^81637744 is an apocalyptic number.

It is an amenable number.

81637744 is a deficient number, since it is larger than the sum of its proper divisors (76535416).

81637744 is a wasteful number, since it uses less digits than its factorization.

81637744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5102367 (or 5102361 counting only the distinct ones).

The product of its digits is 112896, while the sum is 40.

The square root of 81637744 is about 9035.3607564945. The cubic root of 81637744 is about 433.8074421679.

The spelling of 81637744 in words is "eighty-one million, six hundred thirty-seven thousand, seven hundred forty-four".